The frequency of a single episode of otitis media (OM) is so high that a genetic predisposition is unlikely to be identified. However, the predisposition to recurrent episodes of acute otitis media (AOM) and to persistent middle ear effusion (MEE) may have a significant genetic component. The research design for this study is a sibling-pair linkage study. We have recently estimated for a twin/triplet study of OM that the susceptibility to middle ear disease has a heritability of approximately 0.72 by two years of age. This suggests that it is feasible to identify a major gene or genes contributing to susceptibility using a genome-wide screen of genetic markers in affected sibling pairs and identity-by-decent (IBD) analysis. The proposed study will recruit a sample of 200 affected sibling pairs and their available parents for the identification of susceptibility genes. The parents are being recruited to distinguish IBD for marker alleles from identify-by-state due to chance.